For the purpose of this description, the term belt buffer is understood to mean additional conveyor belts which are inserted in a conveyor line between an entry and an exit conveyor belt to enable an intermediate storage of conveyed products or to specifically extend the conveyor line.
Such belt buffers are used, for example, in the conveying of unpackaged products when it is necessary to provide intermediate storage between the production and the packaging of the products in the event of faults in the packaging area so that no overflow or wastage can occur. This considerably increases the efficiency of production lines. These belt buffers are usually designed on the “first-in/first-out” (FIFO) principle.
Furthermore, with an extension of the conveyor line between production and packaging, the products can also be cooled before they can be packed. As well as the flexible buffering of faults, a belt buffer can therefore also fulfill a cooling function. This is often the case in biscuit production, as the freshly produced products, directly from the oven, are still hot and must be carefully cooled before they can be packed.
In addition, it can be a requirement for the oven to be also able to be run until it is empty in the event of an extended fault in the packaging area, particularly in the case of very valuable complex products which can no longer be fed to a re-work area. In such a case, the buffer section must be designed such that, in all cases, the full length of the oven can be run into the belt buffer.
In these belt buffers, the incoming rows of product are accepted in a synchronized manner in the entry to the belt buffer and indexed without tailback pressure to form formations or product groups. These formations are then transported towards the exit of the belt buffer at higher speed in order to be then fed without tailback pressure and without gaps to the packaging machines.
The entry section of the belt buffer is responsible for the incoming rows of product to be inspected for length and height and distance apart so that only acceptable products pass to the packaging machines. This is usually detected using optical sensors. Non-acceptable rows of product are channeled out in order to prevent subsequent faults.
The requirements for the entry section further consist in the building of product formations without tailback pressure. These product formations are normally made with one or more short belts. The number and length of these belts depends on the type, consistency and dimensions of the product and on the infeed speed.
The formations consist of a defined number of rows of product, which are indexed with regular spacing. The formations are run on belts, the length of which corresponds to the length of the product formation.
The belt buffer consists of any number of buffer belts having the length of a formation or an integral multiple of the formation length, arranged one after the other.
In order to adapt to an available space with limited installation length, a plurality of levels of buffer belts are usually arranged one above the other. The buffer effect is achieved in that the product formations are run towards the exit at higher speed. The formations are then indexed in the exit section of the buffer depending on the packaging speed. Typically, the overall packaging capacity is designed to be 15% to 20% faster than the production capacity. This enables the contents of the buffer to be emptied during production. The formations are usually indexed in rows once more at the exit to the belt buffer. This row separation depends on the number of packaging machines, their speed and the type of packaging.
In the prior art, the products are fed to the different levels at the entry of the belt buffer by means of a deflector in the form of a height-adjustable belt. In the same way, discharge from the different levels at the exit of the belt buffer is carried out with a deflector.